Communicable diseases are those diseases capable of being transmitted from one person to another, or from one species to another. Two major groups of communicable diseases, classified in the International Classification of Diseases (ICD-10), are certain infectious and parasitic diseases (ICD-10 codes A00-B99) and acute respiratory infections (ICD-10 codes J00-J22) which includes influenza and pneumonia as well as other acute upper and lower respiratory infections. In 2003 these two groups accounted for 4.1% of all deaths in Australia (5,429 deaths). Influenza and pneumonia accounted for 66% (3,566) of these deaths. Death rates increase with age, and were greater for males than females in most age groups.In 2003-04, there were 92,892 hospital separations in Australia with a principal diagnosis of infectious and parasitic diseases (AIHW 2005d).

Under the National Notifiable Diseases Surveillance System (NNDSS), state and territory health authorities submit reports of more than 60 communicable disease notifications for compilation by the Australian Government Department of Health and Ageing (DoHA). In 2001, the diseases reported to the NNDSS were revised to include cryptosporidiosis, influenza, pneumococcal disease, Japanese encephalitis, Kunjin virus, Murray Valley encephalitis, anthrax, Australian bat lyssavirus, and other lyssavirus infections. At the same time, diseases that were becoming rare or of less public health significance in Australia, namely chancroid, lymphogranuloma venereum, hydatid disease and yersiniosis were removed from the NNDSS.

The total of notifications to the NNDSS in 2004 was 110,710, a small increase (4.0%) on the 106,191 notifications in 2003 (table 9.28). In 2004 sexually transmitted infections (STI) were the most commonly reported communicable diseases, accounting for 40% of all notifications, followed by gastrointestinal diseases (23%) and blood-borne diseases (17%). Chlamydia was the most common STI (25,189 notifications, 79.5% of total STIs), campylobacteriosis the most common gastroenteritis (15,008 notifications, 59% of total) and hepatitis C (unspecified) was the most common blood-borne disease (12,667 notifications, 66% of total). Compared with 2003, there were increases in notifications of STIs (by 13%) due mainly to increases in chlamydia; gastrointestinal diseases (by 2%) and vaccine preventable diseases (by 17%), while there were decreases in reports of blood borne diseases (by 10%), vector borne diseases (by 11%), and other bacterial diseases such as legionellosis (by 9%) and meningococcal disease (by 29%).

9.28 NATIONAL NOTIFIABLE DISEASE SURVEILLANCE SYSTEM REPORTS

Notifications

Rate(a)

2002(b)

2003(b)

2004

2002(b)

2003(b)

2004

Disease(c)

no.

no.

no.

%

%

%

Blood-borne diseases

Hepatitis B (incident)

392

349

275

2.0

1.8

1.4

Hepatitis B (unspecified)

6,677

6,637

5,861

34.0

33.4

29.1

Hepatitis C (incident)

448

477

361

2.8

3.0

2.3

Hepatitis C (unspecified)

15,906

13,911

12,667

81.0

70.0

63.0

Hepatitis D

23

28

27

0.1

0.1

0.1

Hepatitis n.e.c.

-

-

-

-

-

-

Gastrointestinal diseases

Botulism

-

1

1

-

-

-

Campylobacteriosis

14,736

15,323

15,008

113.3

116.2

112.2

Cryptosporidiosis

3,272

1,225

1,573

16.7

6.2

7.8

Haemolytic uraemic syndrome

11

15

15

0.1

0.1

0.1

Hepatitis A

392

439

315

2.0

2.2

1.6

Hepatitis E

12

14

29

0.1

0.1

0.1

Listeriosis

62

70

65

0.3

0.4

0.3

Salmonellosis

7,848

7,042

7,607

40.0

35.4

37.8

Shigellosis

507

444

518

2.6

2.2

2.6

SLTEC, VTEC(d)

59

52

44

0.3

0.3

0.2

Typhoid

70

51

73

0.4

0.3

0.4

Quarantinable diseases

Cholera

5

2

5

-

-

-

Sexually transmissable diseases

Chlamydial infection

24,426

30,437

35,189

124.4

153.2

175.0

Donovanosis

16

16

11

0.1

0.1

0.1

Gonococcal infection

6,433

6,828

7,098

32.8

34.4

35.3

Syphilis (all categories)

2,015

2,012

2,296

10.3

10.1

11.4

Syphilis < 2 years duration

-

-

596

-

-

3.0

Syphilis > 2 years duration

-

-

1,561

-

-

7.8

Syphilis - congenital

18

15

11

0.1

0.1

0.1

Vaccine preventable diseases

Diphtheria

-

-

-

-

-

-

Haemophilus influenza type b

31

23

15

0.2

0.1

0.1

Influenza (laboratory confirmed)

3,674

3,491

2,073

18.7

17.6

10.3

Measles

32

98

45

0.2

0.5

0.2

Mumps

69

82

102

0.4

0.4

0.5

Pertussis

5,570

5,159

8,557

28.4

26.0

42.5

Pneumococcal disease

2,430

2,303

2,316

12.4

11.6

11.5

Rubella

254

55

33

1.3

0.3

0.2

Rubella - congenital

1

3

1

-

-

-

Tetanus

4

4

5

-

-

-

Vector-borne diseases

Flavivirus NEC

73

61

59

0.4

0.3

0.3

Barmah Forest virus infection

896

1,369

1,052

4.6

6.9

5.2

Dengue

169

854

326

0.9

4.3

1.6

Japanese encephalitis

-

1

1

-

-

-

Kunjin virus

-

19

12

-

0.1

0.1

Malaria

469

598

533

2.4

3.0

2.7

Murray Valley encephalitis

2

-

1

-

-

-

Ross River virus infection

1,458

3,832

4,000

7.4

19.3

19.9

Zoonoses

Brucellosis

39

19

37

0.2

0.1

0.2

Leptospirosis

163

132

166

0.8

0.7

0.8

Ornithosis

212

201

235

1.1

1.0

1.2

Q fever

784

583

440

4.0

2.9

2.2

Other diseases

Legionnellosis

317

340

310

1.6

1.7

1.5

Leprosy

6

5

5

-

-

-

Meningococcal infection

686

578

408

3.5

2.9

2.0

Tuberculosis

1,051

993

1,068

5.4

5.0

5.3

Total

101,718

106,191

110,710

517.9

534.4

550.5

(a) Rate per 100,000 population is calculated using the estimated resident population at the midpoint (30 June) of the relevant calendar year.(b) NNDSS data for 2002 and 2003 revised after consultations with states and territories.(c) Diseases reported to NNDSS from all jurisdictions except hepatitis B (unspecified) not reported from NT; incident hepatitis C not reported from Qld; campylobacteriosis not reported from NSW. Diseases under surveillance for which no notifications were received in the period 2002-04 were plague, rabies, viral haemorrhagic fever, yellow fever, diphtheria, poliomyelitis, anthrax, Australian bat lyssavirus, other lyssavirus n.e.c.(d) SLTEC/VTEC is shiga-like toxins and verotoxin producing E. coli infections.

Source: DoHA 2005a.

HIV AND AIDS

In collaboration with the state and territory health authorities and the Australian Government, surveillance for human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) is conducted by the National Centre in HIV Epidemiology and Clinical Research. This centre is part of the Faculty of Medicine, University of New South Wales and is funded primarily by DoHA.

At 31 December 2004 the cumulative number of cases of newly diagnosed HIV infections (since 1985) was 24,243. The annual number of new HIV diagnoses reached a low of 714 in 1999, after which there was a continual increase (to 886 in 2004). The cumulative number of AIDS diagnoses, adjusted for reporting delay, was 9,618 (since 1981) and there was a total of 6,590 deaths following AIDS (table 9.29).

There has been a reduction in numbers of new AIDS diagnoses since the late 1990s, which has been due to the decline in HIV incidence that took place in the mid-1980s, and the use, since around 1996, of effective combination antiretroviral therapy for the treatment of HIV infection. In Australia, an estimated 53% of all people living with HIV infection are receiving antiretroviral treatment. However, the long-term effectiveness of antiretroviral treatment in preventing progression of HIV infection remains unknown.

(a) Not adjusted for multiple reporting. (b) AIDS cases diagnosed and deaths following AIDS in 2002, 2003 and 2004 were adjusted for reporting delays; AIDS cases diagnosed and deaths following AIDS in previous years were assumed to be completely reported.(c) The number of HIV/AIDS diagnoses for each year may be revised over time due to late reports, updated information on exposure and testing history for reported cases, and removal of previously unrecognised duplicate diagnoses.

Source: National Centre in HIV Epidemiology and Clinical Research, 'HIV/AIDS, viral hepatitis and sexually transmissible infections in Australia Annual Surveillance Report 2005', National Centre in HIV Epidemiology and Clinical Research, The University of New South Wales, Sydney, NSW; Australian Institute of Health and Welfare, Canberra, ACT. 2005.

Transmission of HIV in Australia continues to be mainly through sexual contact between men (77% in 2004). Exposure to HIV was attributed to heterosexual contact in 23.2% of new diagnoses and to injecting drug use in 4.2% of diagnoses (table 9.30). Mother-to-child transmission of HIV remains rare in Australia.

9.30 CHARACTERISTICS OF CASES OF NEWLY DIAGNOSED HIV INFECTION(a), Number of cases and proportion of total cases

Year of diagnosis(b)

Units

Prior
to 1996

1996

1997

1998

1999

2000

2001

2002

2003

2004

Total

Total cases

no.

16,940

900

821

753

714

755

765

848

861

886

24,243

Males

%

93.4

91.9

91.2

89.4

87.0

89.5

89.2

87.8

88.7

89.0

92.1

State/territory

New South Wales

%

59.8

50.7

52.6

53.1

52.5

48.7

45.0

47.9

49.2

45.7

56.7

Victoria

%

20.3

20.2

22.0

18.5

19.2

25.2

27.1

25.8

23.7

24.2

21.1

Queensland

%

9.2

16.0

13.9

13.8

17.1

15.1

13.6

15.3

14.8

17.5

11.0

South Australia

%

3.5

5.1

4.3

4.6

3.2

3.0

5.6

3.5

5.1

5.6

3.8

Western Australia

%

5.0

6.3

4.9

6.9

5.7

6.1

6.5

5.3

6.0

4.6

5.2

Tasmania

%

0.4

0.3

-

0.4

0.4

-

0.7

0.6

-

0.6

0.4

Northern Territory

%

0.5

0.6

1.3

1.6

0.7

0.4

0.5

0.9

0.6

0.9

0.6

Australian Capital Territory

%

1.2

0.8

1.0

1.1

1.1

1.5

1.0

0.6

0.6

0.9

1.1

Exposure category(c)

Male homosexual contact

%

80.3

75.3

72.9

65.7

65.4

68.3

66.3

70.8

73.6

68.4

76.9

Male homosexual contact and injecting drug use

%

4.1

4.2

4.8

4.7

6.5

3.6

5.1

4.1

4.3

3.9

4.3

Injecting drug use(d)

%

4.4

2.7

3.1

3.6

5.4

4.3

5.6

2.6

3.8

4.2

4.2

Heterosexual contact

%

7.0

16.7

18.2

24.9

21.8

23.3

22.4

22.1

18.1

23.2

11.6

Haemophilia/coagulation disorder

%

2.1

-

-

0.1

0.5

-

0.1

-

-

-

1.4

Receipt of blood/tissue

%

1.6

0.2

0.1

0.6

0.3

-

-

-

-

0.1

1.1

Mother with/at risk of HIV infection

%

0.3

0.9

0.9

0.4

0.1

0.4

0.4

0.3

0.2

0.1

0.4

Health care setting

%

0.1

-

-

-

-

-

-

0.1

-

-

0.1

Other/undetermined

%

18.9

9.4

8.1

7.6

9.0

8.1

7.2

9.9

7.7

9.6

15.8

(a) Not adjusted for multiple reporting.(b) The number of HIV/AIDS diagnoses for each year may be revised over time due to late reports, updated information on exposure and testing history for reported cases, and removal of previously unrecognised duplicate diagnoses.(c) The ‘Other/undetermined’ category was excluded from the calculation of the percentage of cases attributed to each HIV exposure category.(d) Excludes males who also reported a history of homosexual/bisexual contact.

Source: National Centre in HIV Epidemiology and Clinical Research, 'HIV/AIDS, viral hepatitis and sexually transmissible infections in Australia Annual Surveillance Report 2005', National Centre in HIV Epidemiology and Clinical Research, The University of New South Wales, Sydney, NSW; Australian Institute of Health and Welfare, Canberra, ACT, 2005.

CHILDREN'S IMMUNISATION

Immunisation programs for children are recognised as an effective public health intervention, and have been responsible for eradicating or minimising infectious diseases such as diphtheriea, whooping cough and polio as major causes of death and disability in Australia.

The Australian Childhood Immunisation Register (ACIR), which commenced operation on 1 January 1996, aims to provide accurate and comprehensive information about immunisation coverage for all children under the age of seven. The register is administered by the Health Insurance Commission (HIC) on behalf of DoHA and is a key component of initiatives to improve the immunisation status of Australian children.

Immunisation coverage goals for Australia for the year 2000, recommended by the National Health and Medical Research Council (NHMRC), called for 90% or more coverage of children at two years of age, and near universal coverage of children at school-entry age, against diphtheria, tetanus, pertussis (whooping cough), poliomyelitis, measles, mumps, rubella and Hib (Haemophilus influenza type b).

ACIR data indicated, at 30 June 2005, 91% of one year olds, 92% of two year olds and 83% of six year olds were fully immunised according to the NHMRC Recommended Australian Standard Vaccination Schedule. State summaries by age group based on ACIR data are contained in the quarterly Communicable Diseases Intelligence Bulletin,published on the HIC web site at: <http://www.hic.gov.au>.